Use of a Shear Reduction Surface in Pre-hospital Transport

Ann N. Tescher, APRN, PhD, CCRN, CCNS, CWCN1, Kathleen Berns, APRN CNS, MS, CFRN2, Evan Call, MS3, Patrick Koehler, BS, RRT, RPFT4, Kip Salzwedel, AS, RRT4, Heather McCormack, PT, DScPT, CWS5, Lucas Myers, BA2, Christine Lohse, MS6, Jay Mandrekar, PhD6, Marianne Russon, BS7 and Josh Burton, BS, PhD(c)7, (1)Mayo Clinic Rochester, St Marys Campus, Mayo Clinic, Rochester, MN, (2)Mayo Medical Transport, Mayo Clinic, Rochester, MN, (3)Support Service Standards Initiative, Washington, DC, (4)Respiratory Care, Mayo Clinic, Rochester, MN, (5)Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, (6)Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, (7)EC Services, Centerville, UT
    1. Purpose: Examining effectiveness of a commercial anti-shear mattress overlay (ASMO) in reducing shear and pressure, and increasing comfort on an ambulance stretcher.

    2. Methods: Randomized trial, cross-over design. Thirty healthy adult volunteers in 3 BMI categories (blinded to the intervention) served as their own controls. The ASMO was randomly placed on a standard ambulance stretcher. PREDIA shear/pressure sensors were applied to the sacrum, ischial tuberosity (IT), and heel. The stretcher was placed in sequential 0°, 15°, and 30° elevations. The ambulance travelled over a closed course achieving a maximum of 30 mph, with 5 complete stops at each HOB elevation for a total of 900 trials. Subjects rated discomfort on a 0-10 scale after each series of 5 runs.

    3. Results:  The peak shear difference between surfaces was -0.89, indicating that after adjusting for elevation, sensor location, BMI, type of ambulance, and driver, starting pause peak shear levels were 0.89 Newtons lower for ASMO compared with standard surface  (p=0.057). Compared with 0°, elevations of 15° and 30° increased these levels by 2.41 (p<0.001) and 3.44 (p<0.001) Newtons, respectively.  Compared with sacrum, IT and heel increased pre-run shear levels by 2.54 (p<0.001) and 1.01 (p=0.079) Newtons, respectively.  The peak pressure difference between surfaces was -1.69, indicating pre-run peak pressure levels were 1.69mmHg lower for ASMO compared with standard surface (p=0.070).  Discomfort was lower on the ASMO than standard surface at 0° and 30° (p=0.004, p=0.014).   Both surfaces had increased discomfort moving from 0° to 30° (p=0.005 and 0.039 respectively).  Differences in discomfort and shear between the two surfaces were not associated with BMI.

    4. Conclusion: For all measurements studied, ASMO reduced levels of shear and pressure, although these differences did not reach statistical significance. Discomfort was reduced on ASMO. Further study is indicated for medical transport.